The European Union cast doubt Wednesday on hopes of a quick resumption of stalled nuclear talks with Iran, saying a message from Tehran to kickstart the negotiations offered nothing new.

While Iran announced it had sent a letter Tuesday to EU foreign policy chief Catherine Ashton agreeing to a new round of talks with six world powers, her office suggested a fresh bid to resolve the festering dispute was premature.

"We are surprised to hear the Iranians talking about meetings. They have not been in touch with us with any proposals," said Ashton's spokeswoman Maja Kocijancic.

"On its own, Dr Jalili's letter does not contain anything new and does not seem to justify a further meeting," she said, referring to chief Iranian nuclear negotiator Saeed Jalili.

"We will be in touch with the Iranians with the aim to create the basis for a new dialogue," the spokeswoman added.

Western diplomats said Jalili's letter had arrived out of the blue, with no prior discussion through usual diplomatic channels and no fresh offers laid out in the message after the last round of talks in Istanbul collapsed in January.

At those talks, which Ashton described in a February letter to Jalili as "disappointing", Iran insisted its sensitive uranium enrichment work was not up for debate and instead demanded international sanctions be lifted as a precondition.

Ashton coordinates the long-stalled talks with Iran on behalf of the five permanent members of the UN Security Council -- the United States, Britain, France, China and Russia -- and Germany.

World powers suspect Iran is masking a weapons drive under the pretext of a civilian nuclear programme, a charge Tehran denies.

Ashton's February 11 letter lays out two areas "to rebuild mutual trust between us". The first is a fuel swap for the Tehran research reactor, the second suggests ways to strengthen monitoring in Iran by the Vienna-based IAEA nuclear watchdog.

"On our side we continue to believe that a negotiated solution can be found which would restore confidence in the exclusively peaceful nature of your nuclear programme."

But Jalili did not refer to these suggestions, said a diplomat who asked to remain anonymous.

"We do not want a repeat of Istanbul," said the source. "If there's a meeting we need real substance. This would involve a common understanding of the agenda."

In his letter, Jalili offered to talk of regional developments and other world issues but stayed clear of the nuclear controversy, a diplomat said.

Iran says negotiations must revolve around a package given to world powers three years ago that does not specifically mention its own programme but insists on talking about global nuclear disarmament and world security.

Jalili said "the developments in recent months have shown that Iran's proposal package three years ago was based on the correct understanding of the realities."

He added that "respecting the nation's rights and refraining from pressure are the two main pillars of cooperation."

On Monday, Iranian President Mahmoud Ahmadinejad said Tehran welcomes "the wish of the 5+1 Group to return to the path of negotiations."

"We have always been ready for talks, and we are ready today," he said, adding that the nuclear issue can be solved "in an hour-long meeting."

"Based on law, it is the Iranian nation's right to acquire the enrichment technology," he said.

"But the reality is that other policies under the guise of the nuclear issue are put on the table. It is clear that some Western governments do not want us to develop (in the nuclear field)."

Iran's nuclear programme has already been the subject of six UN Security Council resolutions, plus unilateral measures imposed by the United States and the EU.